Bucket drive for overhead mining machine



Feb. 4, 1969 F. v. M CAY, JR 3,425,573

BUCKET DRIVE FOR OVERHEAD MINING MACHINE I Filed Sept. 1, 1967 Sheet of a FIG. I

INVENTORV FRANK V. MC CAY. JR.

QMw-M ATTORNEY Feb. 4, 1969 F. v. MCCAY, JR- ,5

BUCKET DRIVE FOR OVERHEAD MINING MACHINE Filed Sept. 1, 1967 Sheet 2 of s 39 I 1 f x y I J Q N IE V A 31 i 42 2s i 1 3e -34. )l 4a I] I l I I ll.

II I l Ii 1, E l :1: 49 J i; i 5| 1 45 4 32 mvmmzz.

27 FRANK V. MCCAY,JR FIG. 3 BY 2 I g ATTORNEY Feb. 4,1969 F. v. M cAY, JR 3,425,573

BUCKET DRIVE FOR OVERHEAD MINING MACHINE Filed Sept. 1, 1967 Y Sheet 3 of a FIG; 4

INVENTOR. FRANK v. MC CAY,JR

ATTORNEY United States Patent Ofiice 3 Claims Int. Cl. E02f 3/00 ABSTRACT OF THE DISCLOSURE A mining machine of the type having a shovel bucket mounted on paired rocker arms connected to a bucket drive system having a non-reversing motor to raise the bucket from a lower digging position up through an overhead path for. rearward discharge. A cam clutch onl-one shaft in the system allows the [bucket to be raised by the motor but blocks reverse motion to provide a positive mechanical lock against reverse rotation to hold; the bucket in an elevated position without putting a reverse load on the motor. A normally engaged releasable clutch connects the bucket to the one way shaft carrying the cam clutch and to the motor. Upon disengagement of the releasable clutch the bucket is free to fall from the elevated position.

This invention relates generally to mining machines and more specifically to improved bucket drive means for mining machines of the type having a shovel bucket mounted on paired rocker arms and a bucket drive -system which operates on the arms, to raise the bucket from a lower digging position up through an overhead path for discharge to the rear.

In theusual prior machine of this type the bucket is pulled by a chain winding on a reel driven by a reversible motor, the motor serving also as the brake if it is desired to hold the bucket in an elevated position. The motor is reversed to enable lowering of the bucket and this often results in a tangled drive chain due to the unloaded mibjtor overrunning the bucket. An additional problem is :that the motor isl'not a reliable brake for holding even an unloaded bucket elevated. Also, particularly in the case of air motors, a reversible motor is less eflicient than is a non-reversible motor.

A primary object of this invention is to provide a bucket drive system for machines of the type under discussion having a positive mechanical brake blocking reversal of the system independently of the motor thereby holding the bucket in any desired elevated position without reverse strain von the motor.

A primary object of this invention is to provide a bucket drive system for machines of the type under discussion having a positive mechanical brake blocking reversal of the system independently of the motor thereby holding the bucket in any desired elevated position without reverse strain on the motor.

A further object is to provide a bucket drive system utilizing a pull chain and takeup reel in which the takeup reel is disengageable from the motor to allow the bucket to gravity fall to digging position.

A related object is the provision of means for releasing the takeup reel from engagement with both the brake and the motor at the same time whereby the chain may unwind and the bucket fall freely.

In order that the invention may be more readily understood and carried into effect, reference is made to the accompanying drawings and the description thereof which are offered by way of illustration only and not in limitation of the invention, the scope of which is defined by the appended claims.

3,425,573 Patented Feb. 4, 1969 In the drawings:

FIG. 1 is a side elevational view, partially cut away, showing a mining machine embodying the invention.

FIG. 2 is a partial view taken from the same side as in FIG. 1 but with the motor removed to more clearly show the remainder of the bucket drive system.

FIG. 3 is a sectional viw of the bucket drive system taken in the plane of lines. 3-3 of FIG. 2.

FIG. 4 is a schematic view illustrating operation of the bucket drive.

In the embodiment illustrated, the mining machine 10 comprises a lower wheeled frame 11 which supports an upper body section 12. A pair of rails 13 are secured along opposite side edges of the upper body and paired rocker arms 14 are arranged to roll on the rails to elevate a bucket 16 from a lower digging position through an overhead path to discharge rearwardly -of the machine. The bucket and arms are 'pulled through the digging and discharge cycle by a flexible chain 17 winding on a takeup reel 18 driven by an air motor 19 through the drive system of the invention, all as shown in greater detail in FIGS. 2-4.

The motor 19 is a non-reversing air motor controlled by a suitable valve 21 which receives air through an inlet 22 and distributes it either through conduit 23 to the motor or through a conduit 24 to a clutch control as hereinafter described.

The bucket drive illustrated in FIG. 2 comprises generally a clutch 26 having a power inputl, shaft 27 by which motor output is received and transmitted through a gear train to the takeup reel 18 which is functionally connected to the bucket by the chain 17 or other flexible draft means.

The opposite end of the shaft 27 is connected to a cam clutch 28 which is conventional in construction and operates simply to allow the,shaft 27 to be rotated in one direction by the motor to drive the takeup reel pulling the bucket through the digging and discharge cycle but blocks reverse rotation of shaft 27 and all elements connected thereto. Cam clutches or, similar ratchet arrangements are well known hence furtherdescription of its operation and construction are unnecessary.

In addition to the can; clutch a normally engaged releasable clutch is also provided to controllably connect and disconnect the bucket to the cam clutch and the drive system.

A clutch hub 29 is splined to the drive shaft 27 and has a concentric clutch gear 31 secured thereto. (For convenience, in FIG. 4, the hub and gear are shown as a single element 29.) Suitable gear teeth on the periphery of the clutch gear 31 engage mating internal teeth on an externally concentric clutch drum 32. Secured to and extending inwardly from the wall of the clutch drum 32 are outer clutch plates 33.

Complemental inner clutch plates 34 are provided with their free edges interposed between the outer plates 33 and their opposite edges connected to an inner clutch plate gear 36 which is in turn splined to an output pinion 37 that is formed as a hollow shaft concentric with and journalled for rotation about the shaft 27. A series of clutch springs 38 maintain the clutch plates 33 and 34 normally in engagement thus eifectively connecting the shaft 27 to the output pinion 37 when the clutch is engaged. An idler gear 39 engages the output pinion and transmits rotation through additional gearing to drive the takeup reel 18. In this arrangement, the clutch is normally engaged and the bucket is operatively connected to the cam clutch and to the motor.

A reaction ring 42 is fixedly mounted on the outer surface of the clutch drum; and a pair of rollers 43 mounted on a yoke 44 (shown in dotted lines in FIG. 2)

are used to disengage the clutch as desired. Adjacent the terminal ends of yoke 44 are pivot members 45 seated in sockets 46 in the clutch housing. Suitable springs 47 bear against the ends of the yoke outboard of the pivots to urge the rollers 43 out of engagement with the reaction ring.

.A shaft 48 connects to a crank arm 49 the free end of which extends into an actuating device comprising a cylinder 51 and a piston 52 which may be driven by air introduced through a conduit 24. When air is admitted to the cylinder the piston presses against the crank arm 49 to rotate the yoke about the 'pivots 45 and move the rollers into engagement with the reaction ring.

So long as the valve is in either the raise or neutral positions, the friction clutch 26 is engaged, the cam clutch and motor are operatively connected intothe system, the takeup reel is blocked from reverse rotation and the bucket cannot return to the lower position. However, unusual jolts or stresses on the drive will be accommodated by slippage in the frictional clutch 26.

To elevate the bucket, the valve is moved to the raise position whereby air is supplied to the-motor and the bucket is pulled through the digging and discharge cycles.

To freethe takeup reel and permit the bucket to fall, the valve is moved to the lower position admitting pressured air into the cylinder 51 to drive the piston 52 against the crank arm 49 to disengage the' clutch and uncouple the reel from the shaft 27.

In normal use, the operator will move the valve to the lower position when the bucket approaches the discharge position.

From the foregoing it is evident that in its simplest form the drive system includes afirst shaft 27 driven by a motor, a second shaft 37 operatively connected (through the additional gears, the takeup reel and the chain) to the arm, a cam clutch 28 operable on the first shaft 27 to enable one way rotation thereof while blocking its reverse rotation and additional clutch means 26 releasably connecting the first and second shafts whereby when the clutch is engaged the shafts are engaged so that the motor may drive the bucket upwardly from digging to discharge and the cam clutch will provide a positive mechanical brake against reverse bucket movement until the clutch is disengaged whereupon the bucket will return by gravity to the lower position.

Although the invention has been. described with specific reference to a machine having paired rocker arms riding on rails and powered by an air motor it is to be understood that it has equal application to machines using only one driving arm and/or in which the bucket arms pivot about a fixed rather than a moving axis and/or are driven by motors other than air motors. Also, it is obvious that the various elements may be arranged differently in the system without departing from the scope or spirit of the having a bucket carried on the forward end of an arm mounted for movement to raise the bucket from a lower digging position to an upper discharge position and a motor driven bucket drive means for effecting said bucket movement, said bucket drive means comprising a first shaft mounted to be rotatably driven by a motor, a second .shaftgoperatively connected to said arm, a cam clutch operable on'said first shaft to enable one way rotation thereof while blocking reverse rotation, and additional clutch means releasably connecting said first and second shafts whereby when said additional clutch means is engaged said bucket may be moved upwardly by rotation of said first'shaft in one direction and held in elevated position by operation of said carn clutch and when said additional clutch is disengaged said second shaft is freely rotatable to enable gravity fall-of said bucket to a lower position.

,2. A bucket drive according to preceding claim 1 in which said second shaft comprises a hollow shaft concentric with and journalled for rotation about said first shaft and the operative connection between said second shaft and the bucket comprises a takeup reel driven by said second shaft and flexible draft means interconnecting said takeup reel and said arm.

3. Av bucket drive according to preceding claim 2 in which said additional clutch comprises a frictionclutch.

References Cited UNITED STATES PATENTS 2,843,213 7/1958 Schwartz 2l4-- 13l X HUGO O. SCHULZ, Primary Examiner. 

